Adjustable knee tibial trial insert

ABSTRACT

An adjustable tibial trial insert includes an upper plate having an upper articular surface and a lower plate. A height-adjustment mechanism of the insert is coupled to and positioned generally between the upper plate and the lower plate and is configured to move between a closed position where the upper and lower plates are adjacent each other and an opened position where the upper and lower plates are spaced-apart from each other in order to adjust a height or thickness of the insert.

This is a divisional application of copending U.S. patent applicationSer. No. 10/997,493, which was filed on Nov. 24, 2004, now U.S. Pat. No.7,309,363 the entirety of which is hereby incorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to orthopaedic surgical trialimplants, and more particularly to an orthopaedic tibial insert or traytrial.

BACKGROUND

During knee replacement surgery tibial trials, such as tibial trialtrays and tibial trial inserts, are used to assist a surgeon inpreparing the tibial surface for implantation of the tibial portion ofthe artificial knee. A surgeon often uses a tibial insert to determinethe tibial implant size, to make the appropriate cuts and reams in thebone, and to ensure a proper alignment and tibial component thicknessprior to implanting the tibial components themselves, for example.

Such a procedure typically entails making an initial cut on the proximaltibial portion of the knee; determining a preferred size trial trayand/or insert; placing the selected trial tray and/or insert over thetibial surface; and performing a trial reduction to ensure proper tibialcomponent thickness and alignment. If, for example, after performing thetrial reduction, the surgeon or other technician determines that thetrial insert and/or tray is not of the proper thickness, the trialinsert and/or is often removed and replaced with a different trialinsert and/or tray having a different thickness. In other applications,one or more spacers or other modular components of the tibial trialinsert may be inserted into the trial insert to adjust the thickness.These processes may continue until the appropriate thickness of thetrial insert and/or tray is determined.

SUMMARY

The present invention comprises one or more of the features recited inthe appended claims or the following features or combinations thereof:

An adjustable tibial trial insert includes an upper plate having anupper articular surface and a lower plate. The tibial trial insert maybe used with a tibial tray; therefore, the lower plate may include alower surface configured to engage a top surface of the tibial tray. Aheight-adjustment mechanism of the insert is coupled to and positionedgenerally between the upper plate and the lower plate. Theheight-adjustment mechanism is configured to move between a closedposition where the upper and lower plates are adjacent each other and anopened position where the upper and lower plates are spaced-apart fromeach other.

The height-adjustment mechanism includes drive means coupled to theupper plate and the lower plate and an actuator coupled to the drivemeans and to one of the upper and lower plates. The actuator may includea lever pivotably coupled to one of the upper plate and the lower plate.The height-adjustment mechanism may also include a height-adjustmentlever pivotably coupled to one of the upper plate and the lower plate ata pivot point. A tie-rod may be coupled to the height-adjustment leverat a distance spaced-apart from the pivot point of the height-adjustmentlever such that pivoting movement of the height-adjustment lever aboutthe pivot point moves the tie-rod in a generally lateral direction. Theactuator may also include a knob and a link pivotably coupled to thedrive means and coupled to the knob for rotation with the knob.

In some embodiments, the drive means of the height-adjustment mechanismmay include a first linkage pivotably coupled to the upper plate and thelower plate and a second linkage pivotably coupled to the upper plateand the lower plate.

In other embodiments, the drive means may include a wedge having a firstangled surface and a second angled surface. The upper plate may includea lower angled surface slidingly engaged with the first angled surfaceof the wedge and the lower plate may include an upper angled surfaceslidingly engaged with the second angled surface of the wedge.

In still other embodiments, the drive means may include a first crossbarcoupled to the actuator, pivotably coupled to the upper plate, andpivotably coupled to the lower plate. The drive means may furtherinclude a second crossbar pivotably coupled to the upper plate andpivotably coupled to the lower plate. The upper plate may include anupper channel and the lower plate may includes a lower channel such thatthe first crossbar may be received within the upper channel for slidingmovement within the upper channel and the second crossbar may bereceived within the lower channel for sliding movement within the lowerchannel. The drive means may also include a third crossbar pivotablycoupled to the upper plate, pivotably coupled to the lower plate, andspaced-apart from and generally parallel to the first crossbar. Thesecond crossbar may be positioned between the first and third crossbars.

Illustratively, one of the upper and lower plates may include acalibrated scale to visually indicate a height of the adjustable tibialtrial. Further, one of the upper plate and the lower plate may include acavity and at least a portion of the height-adjustment mechanism may bepositioned within the cavity. A slot may be formed in a front surface ofone of the upper and the lower plate for communication with therespective cavity. The height-adjustment lever may be received throughthe slot. Further, the slot may include a plurality of detents formed toreceive the height-adjustment lever to lock the height-adjustment leverin a particular position.

In other embodiments, an adjustable tibial trial insert includes anupper plate having an upper articular surface, a lower plate, and aheight-adjustment mechanism including drive means coupled to the upperplate and the lower plate for moving the upper plate and the lower plateaway from each other. The height-adjustment mechanism also includes atie-rod pivotably coupled to the drive means and an actuator pivotablycoupled at a first pivot point to one of the upper plate and the lowerplate and pivotably coupled to the tie-rod at a second pivot pointspaced-apart from the first pivot point.

In still other embodiment, an adjustable tibial trial insert includes anupper plate having an upper articular surface, a lower plate, and anon-threaded height-adjustment mechanism including drive means coupledto the upper plate and the lower plate. The drive means is movablebetween a closed position and an opened position to adjust a height ofthe insert. The height-adjustment mechanism further includes an actuatorcoupled to the drive means and to one of the upper and lower plates tomove the drive means between the closed and opened positions.

The above and other features of the present disclosure will becomeapparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of the tibial trial insert of the presentdisclosure shown in a closed position;

FIG. 2 is a perspective view of the tibial trial insert of FIG. 1 in anopened position and showing a scissors-type height-adjustment mechanismof the insert for adjusting an overall thickness or height of theinsert;

FIG. 3 is a front view of the insert of FIGS. 1 and 2 shown in theclosed position;

FIG. 4 is a top view of the insert of FIGS. 1-3 with an upper plate ofthe insert having been removed and showing the adjustment mechanism ofthe insert in the closed position;

FIG. 5 is a front view, similar to FIG. 3, showing the insert in theopened position;

FIG. 6 is a top view similar to FIG. 4 showing the adjustment mechanismof the insert in the opened position;

FIG. 7 is a front view of another tibial trial insert of the presentdisclosure showing a sliding-wedge-type height-adjustment mechanism ofthe insert for adjusting an overall thickness or height of the insert;

FIG. 8 is a top view of the insert of FIG. 7 with an upper plate of theinsert having been removed and showing the adjustment mechanism of theinsert in the closed position;

FIG. 9 is a front view of the insert of FIGS. 7 and 8 showing the insertin the opened position;

FIG. 10 is a top view of the insert similar to FIG. 8 showing theadjustment mechanism of the insert in the opened position;

FIG. 11 is a front view of yet another tibial trial insert of thepresent disclosure showing the insert in the closed position;

FIG. 12 is a top view of the insert of FIG. 11 with an upper plate ofthe insert having been removed to reveal a linkage-typeheight-adjustment mechanism of the insert for adjusting an overallthickness or height of the insert;

FIG. 13 is a front view of the insert of FIGS. 11 and 12 showing theinsert in the opened position;

FIG. 14 is a top view of the insert similar to FIG. 12 showing theadjustment mechanism in the fully opened position; and

FIG. 15 is a schematic front view of any one of the tibial insert trialsdisclosed in FIGS. 1-14 showing an alternative rotatable knob actuatorof the height-adjustment mechanism.

DETAILED DESCRIPTION OF THE DRAWINGS

An orthopaedic tibial trial insert 10, as shown in FIGS. 1-6, includesan upper plate 12 having an upper articular surface 13 including rightand left concave portions 14 and 16 and a lower plate 18 coupled toupper plate 12 and including a lower surface 20 for placement on andengagement with a top surface of an implanted tibial trial tray (notshown), for example. In certain circumstances, the insert 10 may also beplaced directly on a surface of the patient's tibia, for example. Insert10 further includes a height-adjustment mechanism 22 (shown in FIG. 2)coupled to both the upper plate 12 and the lower plate 18 in order toallow a surgeon or other technician to adjust a distance between theupper plate 12 and the lower plate 18 to increase or decrease an overallthickness or height 24 of the insert 10. In the illustrative examplesdiscussed below, the height 24 of the insert is measured from the lowersurface 20 of the insert 10 to a low point of the upper articularsurface 13.

The height-adjustment mechanism 22 includes drive means or a drivemechanism movable between a closed position and an opened position foradjusting the height of the insert 10 and an actuator coupled to thedrive means. As is discussed in greater detail below, the actuator isactivated by the surgeon or other technician to move the drive meansbetween the opened and closed positions. Illustratively, in theembodiments disclosed herein, the drive means is coupled to the upperplate 12 and the lower plate 18 and the actuator is coupled to the lowerplate 18. However, the actuator may be coupled to the upper plate 12 aswell.

As mentioned above, the insert 10 is generally provided for cooperativeuse with a tibial trial tray (not shown) or a tibial tray implant (notshown). Tibial trays oftentimes include a plate and a stem coupled tothe plate and received within a pre-drilled hole in the tibia. The lowersurface 20 of the lower plate 18 of the insert 10 is specificallyconfigured to matingly engage and cooperate with an upper surface (notshown) of the tray (not shown). It is the lower surface (not shown) ofthe plate of the tray, therefore, which is configured to engage andcooperate with a proximal end of the tibia. In some circumstances,however, the lower surface 20 of the lower plate 18 of the insert may beconfigured to engage and cooperate with the proximal end of the tibia.

Looking now to FIGS. 2-6, it may be appreciated that the drive means ofthe adjustment mechanism 22 is a scissors-type drive means which allowsthe insert 10 to be moved between a closed position, shown in FIGS. 1,3, and 4, where the upper and lower plates 12, 18 are generally adjacentto and engaged with each other and an opened position, shown in FIGS. 2,5, and 6, where the upper and lower plates 12, 18 are spaced-apart fromeach other. In the closed position, the upper and lower plates 12, 18may be engaged with each other as is illustratively shown in FIGS. 1, 3,and 4. Alternatively, however, the upper and lower plates 12, 18 may bespaced-apart from each other in the closed position a distance smallerthan the spaced-apart distance of the upper and lower plates 12, 18 inthe opened position. As mentioned above, the adjustment mechanism 22allows the surgeon and/or other technicians to adjust an overall height24 of the insert 10 after the insert 10 has been inserted into the kneeof a patient. Illustratively, the insert 10 may remain implanted withinthe patient while the height 24 of the insert 10 is adjusted.

The adjustment mechanism 22 includes first and second outer crossbars30, 32 each having a first end 34 coupled to the lower plate 18 and asecond end 36 coupled to the upper plate 12. Illustratively, a pivot pin38 is coupled to the first end 34 each of the first and second outercrossbars 30, 32 and is secured to two opposite, inner walls 40 of thelower plate 18 which define a cavity 42 of lower plate 18, as shown inFIG. 2. The cavity 42 is formed in an upper surface 26 of the lowerplate 18 to receive and stow a portion of the adjustment mechanism 22when the insert 10 is in the closed position to allow the upper surface26 of the lower plate 18 and a lower surface 28 of the upper plate 12 toengage each other, as shown in FIG. 1. Another cavity (not shown) isformed in lower surface 28 of the upper plate 12 to also receive aportion of the adjustment mechanism 22. Illustratively, at least aportion of the adjustment mechanism 22 is received within the cavity 42of the lower plate 18 and the cavity (not shown) of the upper plate 12when the insert 10 is in the opened position as well.

A sliding pin 50 is coupled to the second end 36 of each of the firstand second outer crossbars 30, 32, as shown in phantom in FIGS. 3-6.Illustratively, each end of the pin 50 is received within a channel 52formed within each of two opposite, inner walls (not shown) of the upperplate 12 which define the cavity (not shown) formed in the upper plate12. As is discussed in greater detail below, the sliding pin 50 slideswithin the channels 52 as the adjustment mechanism 22 is moved betweenthe closed and opened positions.

The adjustment mechanism 22 also includes a center crossbar 54positioned between the first and second outer crossbars 30, 32. Thecenter crossbar 54 similarly includes a first end 56 and a second end58. The first end 56 of the center crossbar 54 is coupled to the upperplate 12 by a pivot pin 60 of the adjustment mechanism 22, as shown inphantom in FIG. 5. The second end 58 of the center crossbar 54 iscoupled to the lower plate 18 by sliding pin 62 of the adjustmentmechanism 22, as shown in FIGS. 3-6. Similar to the sliding pin 50, eachend of the sliding pin 62 is received within a channel 64 formed in eachof the opposite inner walls 40 defining the cavity 42 formed in thelower plate 18, as shown in FIG. 2. Further, the sliding pin 62 slideswithin the channels 64 as the adjustment mechanism 22 is moved betweenthe closed and opened positions.

Looking now to FIGS. 4 and 6, the center crossbar 54 further includes acut-out portion 66 formed at the second end 36 of the center cross bar54 to provide two arms 68 of the second end 36 which are each attachedto the sliding pin 62. A tie-rod 70 of the adjustment mechanism 22 ispositioned between the arms 68 of the center crossbar 54, as shown inFIGS. 4 and 6 and is coupled at one end to the sliding pin 62. The otherend of the tie-rod 70 is coupled to a height-adjustment lever 72 whichacts as the user-activated actuator to move the adjustment mechanism 22between the closed and opened positions.

The height-adjustment lever 72 is positioned within the cavity 42 of thelower plate 18 and is pivotably coupled at one end by a pivot pin 74 tothe lower plate 18. A free end of the height-adjustment lever 72 isreceived through a slot 76 formed in a front face 78 of the lower plate18, as shown in FIGS. 1-3 and 5. Illustratively, the slot 76 is incommunication with the cavity 42 of the lower plate 18.

Illustratively, the lever 72 is coupled to the lower plate 18 at a firstpivot point and the tie-rod 70 is pivotably coupled to the lever 72 at asecond pivot point spaced-apart from the first pivot point.Specifically, as shown in FIGS. 4 and 6, the second pivot point of thesecond end of the tie-rod 70 and the lever 72 is positioned between thefirst pivot point of the lever 72 and the free end of the lever 72.Therefore, as the lever 72 is moved counter-clockwise within the slot76, the tie-rod 70 is pulled to the right and as the lever 72 is movedclockwise within the slot 76, the tie-rod 70 is pushed to the left.Although the lever 72 is coupled to the lower plate 18 and the slot 76is formed in the lower plate 18, it should be appreciated that the lever72 may be coupled to the upper plate 12 and the slot 76 may be formed inthe upper plate 12 to receive the lever 72 therein.

In use, the height-adjustment lever 72 may be moved within the slot 76of the lower plate 18 by the surgeon or other technician.Illustratively, as shown in FIGS. 1, 2, 3 and 5, the slot 76 iscalibrated at two millimeter intervals between ten and twentymillimeters. Illustratively, the calibrated scale of the slot 76 iscalibrated to reflect a combined height of both the height 24 of theinsert 10 and a pre-known height or thickness of a tray (not shown) uponwhich the insert 10 may rest. By knowing the thickness of the tray,therefore, the calibrated scale also visually indicates the height 24 ofthe insert 10.

When the height-adjustment lever 72 is aligned with the ten millimetermark, for example, the insert 10 is in the closed position, as shown inFIGS. 3 and 4, and the height 24 of the insert 10 plus a height orthickness of a corresponding tray is approximately ten millimeters. Asis discussed above, the illustrative calibrated scale of insert 10 iscalibrated to reflect a height or thickness of the insert 10 as well asthe pre-known height or thickness of the corresponding tray upon whichthe insert 10 may rest. Typically, the thickness of a tray may beapproximately four millimeters and the scale of the insert 10 iscalibrated as such; however, trays having other thickness may be used aswell. A recalibrated scale may be used in such circumstances, forexample. As such, the calibrated scale is indicative of the height 24 ofthe insert 10. Further, it is within the scope of the disclosure for thecalibrated scale to refer only to the height of the insert 10. When theinsert 10 is in the closed position, sliding pins 50 and 62 arepositioned at a left-side of each of their respective channels 52, 64when viewing the insert 10 from the front, as shown in phantom in FIG.3.

As the surgeon or technician moves the free end of the height-adjustmentlever 72 from the left to the right, the tie-rod 70 is pulled (becauseof its point of attachment to the height-adjustment lever 72 at pivotpin 80) from the left to the right, as shown in FIG. 4. As the tie-bar70 is moved to the right, the sliding pin 62 within the channel 64 ofthe lower plate 18 is pulled with the tie-bar 70 to the right as well.As the sliding pin 62 is urged to move to the right, the second end 58of the center crossbar 54 is urged to move to the right as well. Thefirst end 56 of the center crossbar 54 is therefore urged to pivot aboutthe pivot pin 60 to allow the first end 56 of the center crossbar 54 tomove upwardly and raise the upper plate 12 relative to the lower plate18, as shown in FIGS. 5 and 6, to increase the height 24 of the insert10.

As the upper plate 12 is moved upwardly to increase the thickness orheight 24 of the insert 10, the second end 36 of each of the outercrossbars 30, 32 (which is coupled to the upper plate 12) is urged tomove upwardly with the upper plate 12 as well. The sliding pin 50coupled to the second end 36 of the outer crossbars 30, 32 moves to theright within the channel 52 while the first end 34 of the outercrossbars 30, 32 pivots about pivot pin 38 to remain coupled to thelower plate 18. This movement pulls the second end 58 of the centercrossbar 54 to the right, thus driving the scissors-type drive means ofthe adjustment mechanism 22 open and raising the upper articular surface13 of the upper plate 12. In general, therefore, adjustment of theinsert 10 is provided by sliding the lever 72 to the appropriatethickness setting. As the lever 72 is slid to the right, for example,the sliding pin 62 is pulled to the right within the channel 64 via itsconnection through the tie-rod 70. This movement pulls the second end 36of the center crossbar 54 to the right, thus driving the scissors-typedrive means of the adjustment mechanism 22 open to raise the upperarticular surface 13 of the upper plate 12.

A detent or a plurality of detents (not shown) may be provided withinthe slot 76 of the lower plate 18 to receive the height-adjustment lever72 in a locked position. For example, a detent may be formed within theslot 76 at each of the 10, 12, 14, 16, and 20 millimeter thicknesssettings to receive the lever 72 and secure the insert 10 at the desiredheight.

Looking now to FIGS. 7-10, another tibial trial insert 110 is providedwhich is also adjustable between a closed position, shown in FIGS. 7 and8, and an opened position, shown in FIGS. 9 and 10, in order to adjustthe overall height or thickness 24 of the insert 110. Portions of insert110 are the same as or similar to portions of insert 10; as such, likereference numerals have been used to correspond to like components.Illustratively, therefore, the insert 110 includes an alternative upperplate 112 having an upper articular surface 13 including concaveportions 14, 16 and an alternative lower plate 118. An adjustmentmechanism 122 of the insert 110 is positioned between and coupled toboth the upper and lower plates 112, 118. Illustratively, the adjustmentmechanism 122 shown in FIGS. 7-10 includes a sliding-wedge drive meansand an actuator, or lever 172, to move the drive means between theopened and closed positions.

The drive means of the adjustment mechanism 122 includes two slidingwedges 130, 132. Each sliding wedge 130, 132 includes an angled topsurface 134 and an angled bottom surface 136. The angled top surface 134of each of the sliding wedges 130, 132 matingly engages and cooperateswith respective outer or lower angled surfaces 138 of the upper plate112. Similarly, the angled bottom surface 136 of each of the slidingwedges 130, 132 matingly engages and cooperates with respective outer orupper angled surfaces 140 of the lower plate 118, as shown in FIGS. 7and 9. Additionally, in the illustrative embodiment of FIGS. 7 and 9,the angled top surface 134 of the sliding wedges 130, 132 is oblique tothe lower surface of the upper plate 112 and the angled bottom surface136 of the sliding wedges 130, 132 is oblique to the upper surface ofthe lower plate. As such, each of the sliding wedges 130, 132 areslidable relative to the upper and lower plates 112, 118 along angledsurfaces 138 and 140 of the upper and lower plates 112, 118.

The adjustment mechanism 122 of the insert 110 further includes a firsttie-rod 142 coupled to the first sliding wedge 130 and a second tie-rod144 coupled to the second sliding wedge 132. Illustratively, eachtie-rod 142, 144 includes a first end pivotably coupled to therespective wedge 130, 132 by a pin 146 and a second end coupled to aheight-adjustment lever 172 of the adjustment mechanism 122. Similar tothe height-adjustment lever 72 of the adjustment mechanism 22 describedabove with reference to FIGS. 1-6, the height-adjustment lever 172 ispivotably coupled to the bottom plate 118 by the pivot pin 74. The lowerplate 118 includes a cavity (not shown) formed therein and theadjustment lever is coupled to a bottom wall of the cavity.

Illustratively, as shown in FIGS. 8 and 10, the first tie-rod 142 ispivotably coupled to the lever 172 by a pivot pin 150 at a pivot pointspaced-apart from and behind the pivot point of the lever 74. Further,the second tie-rod 144 is pivotably coupled to the lever 172 by a pivotpin 152 at a pivot point spaced-apart from and in front of the pivotpoint of the lever 74. Therefore, as the lever 172 is pivoted about thepivot point 74 in a counter-clockwise direction, as shown in FIG. 8, thefirst tie-rod 142 is pulled to the left or toward the center of theinsert 110 while the second tie-rod 144 is pulled to the right or towardthe center of the insert 110. As each of the respective tie-rods 142,144 are pulled toward the center of the insert 110, the respective firstand second sliding wedges 130, 132 to which each tie-rod 142, 144 isattached are also pulled toward the center of the insert 110.

As shown in FIG. 9, the top angled surface 134 and the bottom angledsurface 136 of each sliding wedge 130, 132 acts against the respectiveangled surfaces 138, 140 of the upper and lower plates 112, 118 to forcethe upper and lower plates 112, 118 to move away from each other as thesliding wedges 130, 132 are pulled inwardly toward the center of theinsert 110. Similarly, as the height-adjustment lever 172 is rotatedabout its pivot point in a clockwise direction, the tie-rods 142, 144and the respective sliding wedges 130, 132 are moved away from eachother or away from the center of the insert 110 to reduce the distancebetween the upper and lower plates 112, 118 and thus reduce the overallheight 24 of the insert 110.

Similar to the lower plate 12 of insert 10, the lower plate 112 includesa slot 76 for receiving the height-adjustment lever 172. The slot 76 isalso calibrated at two millimeter intervals between ten and twentymillimeters. The calibrations provide a visual indication of the overallheight 24 of the insert 110. Further, the slot 76 may include detents(not shown) at each calibrated interval (i.e., at 10 millimeters, at 12millimeters, at 14 millimeters, etc.) to receive the height-adjustmentlever 172 and lock the height-adjustment lever 172 at that location andmaintain the insert 110 at the desired thickness or height 24.

As shown in FIGS. 7 and 8, the insert 110 is in the closed position suchthat the upper and lower plates 112, 118 are adjacent each other and thecombined thickness 24 of the insert 110 and the tray (not shown) uponwhich the insert 110 may rest is illustratively 10 millimeters as shownby the height-adjustment lever 172. As shown in FIGS. 9 and 10, on theother hand, the insert 110 is in the opened position such that the upperand lower plates 112, 118 are spaced-apart from each other and thethickness 24 of the insert 110 is set to the largest setting.Illustratively, the height-adjustment lever 172 is positioned at thetwenty millimeter mark to represent an overall height including theheight 24 of the insert 110 and the height of a tray (not shown) oftwenty millimeters.

Although not shown, each of the sliding wedges 130, 132 may be coupledto the upper and lower plates 112, 118 via a tongue-and-grooveconnection (not shown), for example, between the angled surfaces 134,136 of the wedges 130, 132 and the angled surfaces 138, 140 of therespective upper and lower plates 112, 118. Alternatively, or inaddition to the coupling connection between the wedges 130, 132 and theupper and lower plates 112, 118, the adjustment mechanism 122 may alsoinclude a leaf spring 150 to provide a compressive force between theupper plate 112 and the lower plate 118, as shown in phantom in FIG. 9.As discussed above, the wedges 130, 132 are coupled to the lower plate118 (although the wedges 130, 132 may also be coupled to the upper plate112). Therefore, the spring 150 provides a compressive force between theupper plate 112 and the lower plate 118 to couple the upper and lowerplates 112, 118 together. As such, the spring 150 operates the couplethe sliding wedges 130, 132 to both the upper and the lower plates 112,118.

Illustratively, the lower plate 118 includes two pins or posts 152spaced-apart from each other and the upper plate 112 includes a singlepin or post 154 positioned generally between the posts 152 of the lowerplate 118. The leaf spring 150 is threaded under the posts 152 of thelower plate 118 and over the post 154 of the upper plate 112 to urge theupper and lower plates 112, 118 toward each other. The leaf spring 150or another suitable spring may be provided for the insert 10 shown inFIGS. 1-6 as well to provide a compressive force between the upper andlower plates 12, 18. The adjustment mechanism 122, therefore, actsagainst the compressive force of the leaf spring 150 when the surgeon orother technician is increasing the thickness 24 of the insert 110, butworks with the leaf spring 150 when decreasing the thickness 24 of theinsert 110.

Looking now to FIGS. 11-14, another adjustable tibial trial insert 210is provided. Similar to insert 10, tibial trial insert 210 includes theupper plate 12 and the lower plate 18. Each of the upper and lowerplates 12, 18 include cavities (not shown) formed therein to house anadjustment mechanism 222 of the insert 210 for adjusting an overallheight of the insert 210. The adjustment mechanism 222 illustrativelyincludes a linkage-style drive means and an actuator to operate thedrive means.

As shown in FIGS. 12-14, the adjustment mechanism 222 includes theheight-adjustment lever 172 pivotably coupled to the lower plate 12 bythe pivot pin 74, first and second tie-rods 142, 144 coupled to thelever 172, and a first and second linkage 230, 232 coupled to one of therespective tie-rods 142, 144. As shown in FIGS. 12 and 14, the firsttie-rod 142 is coupled at its second end by the pivot pin 152 at a pivotpoint on the lever 172 spaced-apart from and in front of the pivot point74 of the lever 172 and the second tie-rod 144 is coupled at its secondend by the pivot pin 150 at a pivot point on the lever 172 spaced-apartfrom and behind the pivot point of the lever 172 as viewed from above.As such, the attachment point of the tie-rods 142, 144 to the lever 172of the adjustment mechanism 222 differs from the attachment point of thetie-rods 142, 144 to the lever 172 of the sliding-wedge adjustmentmechanism 122 of the insert 110. Therefore, as opposed to the operationof the sliding-wedge adjustment mechanism 122, counter-clockwiserotation of the lever 172 of the toggle-style drive means of theadjustment mechanism 222 causes the tie-rods 142, 144 to move outwardlyaway from the center of the insert 210, as shown in FIG. 12.

The second, outermost end of each tie-rod 142, 144 is pivotably coupledto one of the respective linkages 230, 232. Each linkage 230, 232includes a first link 234 pivotably coupled to the lower plate 18 and asecond link 236 pivotably coupled to the upper plate 12. The first andsecond links 234, 236 of each linkage 230, 232 are also pivotablycoupled to each other by a central pin 240. Each tie-rod 142, 144 isalso coupled to the central pin 240 of each respective linkage 230, 232.Therefore, as the lever 172 is pivoted in a counter-clockwise directionto increase the height 24 of the insert 210, the tie-rods 142, 144 arepushed outwardly to push the central pin 240 of each linkage 230, 232outwardly as well as upwardly, as shown in FIG. 13. As the central pin240 of each linkage 230, 232 is moved outwardly and upwardly, eachlinkage 230, 232 is moved from a collapsed position toward an expandedposition, as shown in FIG. 13, to move the upper plate 12 and the lowerplate 18 away from each other, thus increasing the overall thickness 24of the insert 210.

Similarly, movement of the lever 172 in a clockwise direction pulls thetie-rods 142, 144 toward each other to also pull the center pin 240 ofeach linkage 230, 232 toward the center of the insert 210 to move eachlinkage 230, 232 to a more collapsed position. As the linkages 230, 232move toward a more collapsed position, the upper plate 12 and the lowerplate 18 move toward each other to decrease the overall thickness 24 ofthe insert 310. As with the inserts 10, 110 discussed above, the lowerplate 18 of the insert 210 may include detents (not shown) formed in theslot 76 of the lower plate 18 which correspond to a particular height orthickness 24 of the insert 210 to receive the lever 172 therein andsecure the insert 210 at that particular desired height.

Although the illustrative actuator of each of adjustment mechanisms 22,122, 222 described above is the lever 72, 172, other actuators may beused. For example, an alternative actuator such as a knob 372 is shownin FIG. 15. The knob 372 may be used to replace the levers 72, 172 ofthe adjustment mechanisms 22, 122, 222 described above, for example, todrive the various scissors-type, wedge, and linkage mechanisms of eachadjustment mechanism. The knob 272 is mounted to a shaft (not shown)which may extend through the upper or lower plates of the insert. Theshaft is then coupled to a vertical bar 274, as shown in FIG. 15, andthe second ends of each tie-rod 142, 144 of the adjustment mechanisms122, 222 or the second end of the tie-rod 70 of the adjustment mechanism22 are then coupled to one end of the vertical bar 274.

Rotation of the knob 372 causes the tie-rods 70, 142, 144 to pull in orpush out depending on the direction of rotation and whether the tie-rods70, 142, 144 are coupled to the vertical bar 274 above or below itspivot point. For example, if the first tie-rod 142 is coupled to thebottom of the vertical bar 274 below the pivot point of the vertical bar274 and the second tie-rod 144 is coupled to the top of the vertical bar274 above the pivot point of the vertical bar 274, clockwise rotation ofthe knob 272 (and thus the vertical bar 274) pulls the tie-rods 142, 144toward the center of the insert and counterclockwise rotation of theknob pushes the tie-rods 142, 144 away from the center of the insert.The connection between the tie-rods 142, 144 and the vertical bar 274may also be switched such that clockwise rotation of the knob 372 pushesthe tie-rods 142, 144 away from each other. In either case, theorientation of the tie-rods 142, 144 with respect to the vertical bar274 may be configured for use with either the sliding wedges 130, 132and/or the linkages 230, 232. The knob actuator 272 may also be usedwith the scissors-type drive means of the adjustment mechanism 22 shownin FIGS. 1-6. For example, the tie-rod 70 may be coupled to the verticalbar 274 at a point spaced away from the pivot point of the vertical bar274 such that rotation of the knob causes the tie-rod 70 to movegenerally laterally and thus move the center crossbar 54. The knob 372may also be calibrated to indicate a particular overall height of thetrial.

While the concepts of the present disclosure have been illustrated anddescribed in detail in the drawings and foregoing description, such anillustration and description is to be considered as exemplary and notrestrictive in character, it being understood that only the illustrativeembodiments have been shown and described and that all changes andmodifications that come within the spirit of the disclosure are desiredto be protected.

There are a plurality of advantages of the concepts of the presentdisclosure arising from the various features of the systems describedherein. It will be noted that alternative embodiments of each of thesystems of the present disclosure may not include all of the featuresdescribed yet still benefit from at least some of the advantages of suchfeatures. Those of ordinary skill in the art may readily devise theirown implementations of a system that incorporate one or more of thefeatures of the present disclosure and fall within the spirit and scopeof the invention as defined by the appended claims.

1. An orthopaedic instrument comprising: an adjustable tibial trial insert, including: (a) an upper plate including (i) an upper articular surface having first and second concave portions configured to receive corresponding femoral condylar surfaces, (ii) a lower surface opposite the upper articular surface; and (iii) a lower angled surface extending from the upper articular surface to the lower surface of the upper plate, (b) a lower plate including (i) a lower surface configured to engage a top surface of a tibial tray, (ii) an upper surface opposite the lower surface of the lower plate, and (iii) an upper angled surface extending from the lower surface of the lower plate to the upper surface, and (c) a height-adjustment mechanism coupled to and positioned generally between the upper plate and the lower plate and configured to move between a closed position where the upper and lower plates are adjacent each other and an opened position where the upper and lower plates are spaced-apart from each other, wherein the height-adjustment mechanism includes a drive coupled to the upper plate and the lower plate and an actuator coupled to the drive and to one of the upper and lower plates, wherein the drive includes a wedge having a first angled surface slidingly engaged with the upper angled surface and a second angled surface slidingly engaged with the lower angled surface, the wedge being positioned such that the first angled surface is oblique to the lower surface of the upper plate and the second angled surface is oblique to the upper surface of the lower plate.
 2. The orthopaedic instrument of claim 1, wherein the height-adjustment mechanism further includes a tie-rod pivotably coupled to the drive at a first end and pivotably couple to the actuator at a second end.
 3. The orthopaedic instrument of claim 2, wherein the actuator is pivotably coupled to one of the upper and lower plates at a first pivot point and the tie-rod is pivotably coupled to the actuator at a second pivot point spaced-apart from the first pivot point.
 4. The orthopaedic instrument of claim 1, wherein the actuator comprises a lever.
 5. The orthopaedic instrument of claim 1, wherein: the lower plate includes a cavity formed therein, the cavity being defined by a bottom wall of the lower plate, and the actuator is coupled to the bottom wall of the lower plate.
 6. The orthopaedic instrument of claim 5, wherein: the lower plate includes an anterior side surface extending from the lower surface of the lower plate to the upper surface of the lower plate, the anterior side surface including a slot defined therein, and the actuator extends through the slot of the lower plate.
 7. The orthopaedic instrument of claim 6, wherein the slot of the lower plate is calibrated.
 8. The orthopaedic instrument of claim 6, wherein the lower plate includes an inner sidewall defining the slot, the inner sidewall having a plurality of detents to lock the actuator in a first position.
 9. The orthopaedic instrument of claim 1, wherein the height-adjustment mechanism further includes a leaf spring positioned to provide an amount of compressive force between the upper plate and the lower plate.
 10. The orthopaedic instrument of claim 9, wherein: the upper plate includes a first post extending therefrom, the lower plate includes a second post and a third post extending therefrom, wherein the leaf spring is coupled to the first, second, and third posts.
 11. The orthopaedic instrument of claim 1, wherein: the lower angled surface of the upper plate is a first lower angled surface and the upper plate further includes a second lower angled surface, each of the first and second lower angled surfaces extending from the upper articular surface to the lower surface of the upper plate, the upper angled surface of the lower plate is a first upper angled surface and the lower plate includes a second upper angled surface, each of the first and second upper angled surfaces extending from the lower surface of the lower plate to the upper surface of the lower plate, the wedge of the drive is a first wedge having a first angled surface slidingly engaged with the first upper angled surface of the lower plate and a second angled surface slidingly engaged with the first lower angled surface of the upper plate and the drive further includes a second wedge having a first angled surface slidingly engaged with the second upper angled surface of the lower plate and a second angled surface slidingly engaged with the second lower angled surface of the upper plate, wherein each of the first and second wedges are positioned such that the first angled surfaces are oblique to the lower surface of the upper plate and the second angled surfaces are oblique to the upper surface of the lower plate.
 12. The orthopaedic instrument of claim 11, wherein the actuator is coupled to the first and second wedges.
 13. The orthopaedic instrument of claim 11, wherein the height-adjustment mechanism further includes: a first tie-rod pivotably coupled to the first wedge at a first end and pivotably coupled to the actuator at a second end, and a second tie-rod pivotably coupled to the second wedge at a first end and pivotably coupled to the actuator at a second end.
 14. The orthopaedic instrument of claim 13, wherein: the first tie-rod is pivotably coupled to the actuator at a first pivot point and the second tie-rod is pivotably coupled to the actuator at a second pivot point spaced apart from the first pivot point.
 15. The orthopaedic instrument of claim 14, wherein the actuator is pivotably coupled to one of the upper and lower plates at a third pivot point spaced-apart from the first and second pivot points. 